An a-frame crane device
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SEAONICS
- Filing Date
- 2024-06-12
- Publication Date
- 2026-05-06
Smart Images
Figure NO2024050135_02012025_PF_FP_ABST
Abstract
Description
[0001]An A-frame crane device Technical field of the invention The invention concerns a crane device as set out by the preamble of claim 1. Background of the invention The so-called "A-frame" crane concept is well known. This crane type comprises a structural frame generally in the shape of the letter A, with two legs arranged at an acute angle and interconnected at one end, or with two legs arranged in parallel and interconnected at one end by a beam. The legs are pivotally connected to a foundation at their respective free ends. The foundation may be on the deck of a ship, barge, or other seagoing vessel. The frame is typically moved (pivoted) by one or more hydraulic cylinders. An example of such crane is described in EP 2054335 B1. The prior art also includes US 6082947, which describes an A-frame crane having a range of motion from about 45 degrees inboard to 45 degrees outboard. This pivoting motion is typically provided and controlled by hydraulic cylinders. A turning sheave is fitted at the intersection of the proximal ends of the A-frame legs, which in one embodiment, when the legs are in parallel relationship, may be bridged by a beam connecting the top of the A-frame's two legs. A lifting cable is passed over the sheave and connected to a load at one end and to a main lifting winch or similar device at the inboard. In use, the load is typically hoisted from the deck with the A-frame positioned inboard, the A-frame is slewed outboard, and the load is lowered over the side or over the stern of the vessel using the winch. Similar prior art A-frame crane concepts are described in US 4324393 A and KR 20210012180 A. There is a need for a crane of the above-mentioned type that is easier to maintain and service, is more compact in the stored (inactive) state, and is more responsive to control inputs that the prior art cranes. Summary of the invention The invention is set forth and characterized in the main claim, while the dependent claims describe other characteristics of the invention. It is thus provided a crane device comprising at least a pair of crane legs interconnected at respective first ends and having respective free ends opposite of the first ends, characterized in that each crane leg is pivotally connected to a respective foundation at a fulcrum, and the fulcrum is located at a first distance from the crane leg free end, whereby the crane leg comprises a first leg portion below the fulcrum and a second leg portion above the fulcrum when the crane legs are in an upright position, and a first control device is operatively connected to the first leg portion and a second control device is operatively connected to the second leg portion, and the control devices are controllable and operable to pivot the crane legs about the respective fulcrum. In one embodiment, the first control device comprises a first winch and a first wire rope extending between the first winch and the first leg portion, and the second control device comprises a second winch and a second wire rope extending between the second winch and the second leg portion, wherein the first and second winches are controllable and operable to selectively reel in or pay out wire rope in order to control a pivoting motion of the crane legs. In one embodiment, the first wire rope extends between the first winch and the leg free end, and the second wire rope extends between the second winch and a second attachment point on the second leg portion. In one embodiment, the first wire rope runs over a sheave in the region of the leg free end and is connected to a first attachment point on the foundation. The first attachment point may be arranged above the first winch, and the first and second winches may be placed on and connected to the foundation. In one embodiment, the first and second winches are powered by respective electric motors. The crane device may be an A-frame crane. Brief description of the drawings These and other characteristics of the invention will become clear from the following description of an embodiment of the invention, given as a non-restrictive example, with reference to the attached schematic drawings, wherein: Figure 1 is a front view of an embodiment of the crane according to the invention; Figure 2 is a side view of the crane illustrated in figure 1, showing three different operational positions; and Figure 3 is a side view of the crane illustrated in figure 1, in an inactive position. Equipment and devices to operate the crane (e.g. power cables, sensors, etc.) have not been illustrated as these are well known in the art and not part of the invention. Detailed description of embodiments of the invention The following description may use terms such as “horizontal”, “vertical”, “lateral”, “back and forth”, “up and down”, ”upper”, “lower”, “inner”, “outer”, “forward”, “rear”, etc. These terms generally refer to the views and orientations as shown in the drawings and that are associated with a normal use of the invention. The terms are used for the reader’s convenience only and shall not be limiting. The invention comprises an A-frame crane, i.e. a crane type comprising a structural frame generally in the shape of the letter "A". In the embodiment illustrated in the drawings, the A-frame crane 1 comprises two legs 1a, 1b arranged in parallel and interconnected at one end by a beam 1c. However, the invention shall not be limited to this configuration, but may comprise other designs, for example an A-frame crane comprising two interconnected legs arranged at an acute angle. One or more lifting sheaves 4a are connected to the top of the A-frame, in the illustrated embodiment via attachment devices 4a on the beam 1c. This is a conventional configuration, also comprising lifting wires running over the lifting sheaves, hooks, and lifting winches (not illustrated). Reference number 2 denotes respective foundations. The foundation may be placed on the deck of a ship, barge, or other seagoing vessel, or on a land facility. Each crane leg 1a, 1b is pivotally connected to a respective foundation 2 at a respective fulcrum 3, dividing the leg into a first (lower) leg portion 14a and a second (upper) leg portion 14b. The fulcrum 3 may comprise a bolt or pin arrangement, or any other pivoting arrangement known in the art. Each fulcrum, and thus the crane legs’ connection to the foundations, is located at a first distance d1 from the respective leg’s free end 12 (see figure 2). The first distance d1 (i.e. the length of the lower leg portion 14a) is dimensioned based on specific operational requirements, but is always less than the length of the upper leg portion 14b (i.e. the second distance d2 between the fulcrum and the legs’ upper end 13). In the illustrated embodiment, the ratio between the first and second distances is approximately 1 / 3. The A-frame crane’s pivoting motion about the fulcrums 3 is thus controlled by applying forces to the lower and upper leg portions 14a, 14b. In general, this is achieved by a first control device connected to the lower leg portion and a second control device connected to the upper leg portion. In the illustrated embodiment, the first control device comprises a first winch and a first wire rope extending between the first winch and the lower leg portion, and the second control device comprises a second winch and a second wire rope extending between the second winch and the upper leg portion. The first and second winches are controllable and operable to selectively reel in or pay out wire rope in order to control the pivoting motion. One embodiment of this principle is illustrated in figure 2, were for each foundation and corresponding crane leg, a first wire rope 5 extends between a first winch 6 and the leg free end 12 (on the lower leg portion 14a), and a second wire rope 9 extends between a second winch 10 and an attachment point 11 on the upper leg portion 14b. Figure 2 illustrates that the first wire rope 5 runs over a sheave 8 in the region of the leg free end 12 and is connected to a first attachment point 7 on the foundation 2, but the invention shall not be limited to this specific configuration. In the illustrated embodiment, the first attachment point 7 is arranged above the first winch 6. The location of the second attachment point 11 is determined based on operational requirements. The first 6 and second 10 winches are preferably placed on and connected to the foundation 2, and preferably are powered by respective electric motors 6a, 10a. Operating the first 6 and second 10 winches will therefore move the A-frame as indicated by the arrow "M" in figure 2. Reference letters "A" and "C" denote forward and aft crane positions, while reference letter "B" denotes a vertical position. The above-mentioned first 5 and second 9 wire ropes are only shown on the crane in position B. In operation, therefore, paying out on the first wire rope 5 from the first 6 winch and reeling in the second wire rope 9 on the second winch 10, will rotate the A-frame to position A, while an opposite winch operation will rotate the A-frame to position C. The A-frame crane pivoting movement M about the fulcrum 3 is thus controlled by manipulation of the winches 6, 10. As the winches are powered by electric motors, the control response is virtually instantaneous. Figure 3 shows the A-frame crane according to the invention in an inactive position. In this position the crane occupies little space compared to the known A-frame cranes. The upper part 13 of the A-frame, where a crane sheave arrangement (4) is located, is also very close to the deck, whereby service, repair or refurbishment may be performed without additional lifting equipment. The elevated fulcrum also shortens the projected length of the A-frame onto the deck, whereby the crane in the parked position has a smaller footprint than a conventional A-frame crane.
Claims
Claims 1. A crane device (1) comprising at least a pair of crane legs (1a, 1b) interconnected at respective first ends (13) and having respective free ends (12) opposite of the first ends, characterized in that each crane leg is pivotally connected to a respective foundation (2) at a fulcrum (3), and the fulcrum (3) is located at a first distance (d1) from the crane leg free end (12), whereby the crane leg comprises a first leg portion (14a) below the fulcrum and a second leg portion (14b) above the fulcrum when the crane legs are in an upright position, and a first control device (5, 6) is operatively connected to the first leg portion (14a) and a second control device (9, 10) is operatively connected to the second leg portion (14b), and the control devices are controllable and operable to pivot the crane legs about the respective fulcrum.
2. The crane device of claim 1, wherein the first control device (5, 6) comprises a first winch (6) and a first wire rope (5) extending between the first winch and the first leg portion, and the second control device (9, 10) comprises a second winch (10) and a second wire rope (9) extending between the second winch and the second leg portion, wherein the first and second winches are controllable and operable to selectively reel in or pay out wire rope in order to control a pivoting motion of the crane legs.
3. The crane device of claim 2, wherein the first wire rope (5) extends between the first winch (6) and the leg free end (12), and the second wire rope (9) extends between the second winch (10) and a second attachment point (11) on the second leg portion (14b).
4. The crane device of claim 2 or claim 3, wherein the first wire rope (5) runs over a sheave (8) in the region of the leg free end (12) and is connected to a first attachment point (7) on the foundation (2).
5. The crane device of claim 4, wherein the first attachment point (7) is arranged above the first winch (6).
6. The crane device of any one of claims 2-5, wherein the first and second winches (6, 10) are placed on and connected to the foundation (2).
7. The crane device of any one of claims 2-6, wherein the first and second winches (6, 10) are powered by respective electric motors (6a, 10a).
8. The crane device of any one of claims 1-7, wherein the crane device is an A- frame crane.